There has been known in the related art a technology which makes it possible to bring up on display a display screen of a portable phone and a plurality of touch switches corresponding to respective operation keys of the portable phone on the display of an in-vehicle device and operate, when any particular touch switch among the touch switches is operated, the portable phone by providing an operation command for an operation key that corresponds to the particular touch switch from the in-vehicle device to the portable phone (see Patent Literature 1).